Duplictated or Copy-Pasted Layers are not identical

[Meitheal]

I recently discovered that in my installation of Gimp, the edges of a png layer that is duplicated or copy-pasted will differ from the duplicate. Generally the duplicate will have parts of the edges cut in or other edges will extend out more. This happens even when no transformations or edits have been performed on the original layer. Hiding and unhiding one layer will show a visual difference, when to my understanding, this shouldn't be the case. Could there be something wrong with my settings that would cause something like this?